A day will come in which men will look upon an animal's murder the same way they look today upon a man's murder.

A diamond is just a lump of coal that stuck to its job.

If you find from your own experience that something is a fact and it contradicts what some authority has written down, then you must abandon the authority and base your reasoning on your own findings.

The motions of men must be such as suggest their dignity or their baseness.

I have always felt it is my destiny to build a machine that would allow man to fly.

When you are painting you should take a flat mirror and often look at your work within it, and it will then be seen in reverse, and will appear to be by the hand of some other master, and you will be better able to judge of its faults than in any other way.

Every obstacle is destroyed through rigor.